Aromatic polyimides have long been known, such as those originally described in Endrey, U.S. Pat. No. 3,179,631 and Gall, U.S. Pat. No. 3,249,588. Further improved polyimides were recently discovered by Manwiller and Anton, and described in U.S. Pat. No. 4,755,555. Each of the above patents is hereby incorporated by reference.
Previous polyimides, with their resistance to high temperatures and overall mechanical properties, have found wide acceptance as coatings and fabricated parts used in technically demanding environments such as jet engines, business machines, automotive components and diverse industrial equipment. However, despite the excellent performance characteristics of previously available polyimide compositions, effort has been directed toward the further improvement of the resistance of polyimide articles to extended exposure to corrosive liquids and high temperature environments.